Dolby Laboratories DP524 Especificaciones descargar pdf (Pagina 30)

6-3

6.2 RS-449 Interface Description

6.2.1 Functional Description

The Dolby Model DP524 provide a standard RS-449 interface in the type DT mode

(data and timing signals only, no handshakes) through 37-pin male D-connectors.

RS-449 is the mechanical specification for a balanced (differential) transmission

system meeting RS-422 and RS-423 electrical specifications. The Model DP524 is

configured as data terminal equipment (DTE), and are typically connected to data

circuit-terminating equipment (DCE) such as RF modems. The DP524 decoder

receives a data clock from a DCE device on the receive timing (RT) pins, and

receives data on the receive data (RD) pins. The internal timing and sample clocks

of the DP524 are phase-locked to ST and RT, respectively. In addition to these

differential signals, the connector also provides pins for signal and chassis ground;

connector pinout is given in the section above. No other RS-449 signals are

supported in these units.

6.2.2 Interface Timing

A “mark,” or “off” state is said to exist when the “+” side of a signal is at a lower

potential than the corresponding “-” side. A “space,” or “on” state exists when the

opposite condition is true. The following timing diagram shows the relationship

between clock and signal lines:

off

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Dolby Laboratories DP524 Especificaciones Pagina 30